There is no admission that the background art discussed in this section legally constitutes prior art.
Commercial establishments, such as quick service restaurants, banks, coffee shops or similar locations provide service by enabling people to drive their automobile or other vehicle or walk up to a communication service point without requiring them to leave the vehicle or enter the building to perform a transaction. Conventionally, a speaker and microphone are located at the service point so that the customer can communicate with service people inside the building using these devices.
There have been a variety of such systems. For example, reference may be made to the following U.S. patents, which are incorporated herein by reference in their entirety:    U.S. Pat. No. 5,512,891 DRIVE-UP STATION VEHICLE DETECTION SYSTEM AND METHOD OF USING SAME;    U.S. Pat. No. 5,305,132 OPTICAL WAVELENGTH COMMUNICATION SYSTEM AND METHOD OF USING SAME;    U.S. Pat. No. 5,253,095 FULL DUPLEX COMMUNICATION SYSTEM AND METHOD OF USING SAME;    U.S. Pat. No. 5,203,017 METHOD AND APPARATUS FOR ESTABLISHING WIRELESS COMMUNICATION WITH MULTIPLE CUSTOMER STATIONS;    U.S. Pat. No. 4,882,770 WIRELESS OPTICAL COMMUNICATION SYSTEM;    U.S. Pat. No. 5,590,407 DRIVE THROUGH WIRELESS ORDER TAKING SYSTEM;    U.S. Pat. No. 6,067,294 WIRELESS COMMUNICATION SYSTEM AND WIRELESS COMMUNICATION APPARATUS; AND    U.S. Pat. No. 6,044,268 SYSTEM AND METHOD FOR PROVIDING INTERCOM AND MULTIPLE VOICE CHANNELS IN A PRIVATE TELEPHONE SYSTEM
In the past, the communications between the service point and the service personnel located in a building have been accomplished by hard-wired half-duplex intercom systems. A service person was required to walk to an intercom station and press a button to talk to the customer and then release the button to hear the customer. This arrangement prevented the service person from moving around the work area to multi-task while still talking to the customer. Moreover, the customer could not talk to the service person when the service person was talking, thereby all too frequently causing confusion and not always completing a transaction accurately. In addition, other service personnel could not listen to the conversation unless they happened to be near the intercom station.
In order to enable the personnel to have more freedom of movement during conversations with customers, a wireless half duplex analog communication system was successfully implemented. The speaker and microphone at the service point were hard wired to a base station inside the building. The service personnel wear or otherwise carry small mobile transceivers and headsets to communicate to the base station and thus to the customer. This arrangement enabled the service person to multi-task, while talking and allowed others to listen in on the conversation so they could help with the service function. This implementation still required the service person to press a button to talk and release the button to hear. Also, even though several service persons were wearing transceivers and listening, only one person could talk at a time or radio interference could prevent all communications under some circumstances.
For the purpose of facilitating the communication, a wireless full-duplex analog communication system was introduced. This full duplex system uses separate transmit and receive radio frequencies and antennas so that full-duplex conversations were possible. The base station transmits on frequency F1 while the mobile units received on frequency F1. Conversely, the mobile transceivers transmit on F2 and the base station receives on F2. This full duplex system enabled transmissions by only one mobile transceiver at a time to prevent radio frequency interference but enabled full duplex communications between the base and the customer to achieve an improved level of accuracy in the communications.
To provide the ability to have more than one mobile unit transmit simultaneously, several base station receivers were used. Within the base station, received audio signals were combined to provide the intercom function between all mobile transceivers. The base station used one transmitter to re-transmit all audio to all mobile transceivers to produce the intercom function where all service personnel could hear all conversations. Thus, the system successfully provided full duplex communication as well as enabling the capability to have two or more service personnel talk simultaneously. Moreover, if the business using this full duplex communication system had more than one service point, separate base stations and frequencies were used to service all lanes of traffic.